1. Field of the Invention
The present invention relates to a cleaning sheet for probe needles, which is capable of substantially simultaneously polishing and removing both film-like adherents leading to inhibition of contactability of needlepoints of a probe card used to measure and inspect the state of completion of each device on a semiconductor wafer (hereinafter simply called “wafer”) and aluminum chips or the like adhered to the entire needlepoints.
2. Description of the Related Art
The following two types are known as cleaning sheets for polishing needlepoints of general probe cards.
The first type of cleaning sheet is a sheet in which polishing grains are contained in a sponge-like substance. The cleaning sheet can be used in a prober or the like in the same manner as a wafer by being attached to the surface of, for example, a used wafer or the like. Needle tips of a probe card attached to the prober or the like are stuck into and spaced away from the cleaning sheet from above and below. Thus, foreign substances (i.e., foreign substances leading to inhibition of electrical contact) adhered to the needle tips and their peripheries are removed.
The second type of cleaning sheet is a sheet fine-meshed in its surface and shaped in a sandpaper fashion. The present cleaning sheet can also be used in a prober or the like in the same manner as a semiconductor wafer by being attached to the surface of, for example, a used wafer or the like. Needle tips of a probe card mounted to the prober or the like are moved up and down so as to be pressed against the cleaning sheet. Since the needle tips of the probe card are inclined toward the cleaning sheet, tip sections of needles are polished while sliding on the surface of the cleaning sheet when the needle tips are pressed against the cleaning sheet, whereby film-shaped foreign substances adhered to the tip sections of the needles are eliminated.
However, the conventional two types of cleaning sheets have the following problems (a) through (c).
(a) The first type of cleaning sheet is made up of the sponge-like substance containing the polishing grains. In contrast, the cleaning sheet performs polishing by repeating such operations as to stick the needle tips from above and below and space them away from above and below. Therefore, there is an effect enough to wipe or clean off pad's chips such as aluminum or the like adhered to the entire needlepoints. Since, however, the pressure for contact between the surface of each needle and the cleaning sheet is small, the ability to polish the film-like inhibitory substance that covers each needle tip is low.
The effect of polishing the tip sections of the needles that need sufficient polishing to ensure contactability is not sufficient because the friction to each polishing grain is low as compared with a side face portion of each needle. Since the needle side face portion is larger than the tip section in friction effect in reverse, the whole needle becomes thin in an alternating succession of polishing. For example, automatic needle alignment based on the recognition of the needlepoints of the prober cannot be recognized because the tip sections of the needles become excessively thin, thus leading to trouble causing an inability to use the needles.
(b) The second type of cleaning sheet has the sandpaper-like surface. The needle tip sections are pressed against the cleaning sheet to polish only the tips of the needles. Therefore, although the effect of polishing the tip sections of the needles is sufficiently obtained, the removal of aluminum chips or the like adhered to the peripheries of the needle tips cannot be expected because the contact portions are limited to the tips of the needles. Since only the tip sections of the needles are polished, the wear of each needle tip proceeds so that the diameter of the needle tip becomes large, thus leading to such trouble that needle traces on measuring pads of the semiconductor wafer increase and the positions of needlepoints are shifted so that the needles are brought into contact with the edge portions of the pads.
(c) As long as the two types of cleaning sheets are used, it is difficult to sufficiently perform the removal of the adherents attached to the whole needle tips and the removal of the film-like adherents applied to the needle tips. Upon their execution, there is a need to alternately exchange the cleaning sheets having their characteristics and carry out two polishing operations. When an attempt is made to normally perform needlepoint polishing by a cleaning sheet for probe needles through the use of an automatic polishing function of a prober without using the number of operator-hours in a probing process, the cleaning sheet that can be set to within a device at a time is limited to one type. Therefore, either one of the two types of cleaning sheets is selected and must be used with being set to the device.